Which of the following genera does NOT belong to the class Deuteromycetes?
According to the NCERT textbook, Alternaria, Colletotrichum, and Trichoderma are the prime examples explicitly listed under the class Deuteromycetes (imperfect fungi), where many act as critical decomposers of litter. In sharp contrast, Ustilago (which famously causes smut disease in crops) and Puccinia (causing rust) are standard examples provided under the class Basidiomycetes. Therefore, Ustilago does not belong to Deuteromycetes.
Ref: NCERT Class 11 Biology > Chapter 2: Biological Classification > 2.3 Kingdom Fungi